Excel and Active Directory...
Once got dumped with an Excel spreadsheet that was not working, asked to take a look. The user support desk bod who'd left 2 years earlier had used VBA hooked up to some some obscure library to add, remove and adjust permissions direct in AD using...an Excel spreadsheet!
One day it stopped working and no one could work out what was wrong. I took one look, marveled at the ingenuity and immediately posted a PDF of "AD Powershell Cmdlets for Beginners" to the support desk and told them start booking some Powershell/AD courses. I then copied the wonderful piece of code for my collection, coded them some basic Powershell scripts to help them get by for a few weeks and told them if they ever ran the Excel sheet again I would report them to the security officer!
Biting the hand that feeds IT
